Electric pen



March 1936. A. JENKINS ET AL 2,633,89?

ELECTRIC PEN Filed March 22, 1935 I N VEN TORS Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE ELECTRIC PEN liam L. Day

Application March 22, 1935, Serial No. 12,360

Claims.

This invention relates to lelectric pens, and more particularly to pens of the type used for making inscriptions on leather or wood or other materials which are adapted to be marked or branded by the imprint of a hot point thereon.

One object of the invention is to provide a relatively simple and inexpensive pen of the character described which is designed to approximate the form of an ordinary ink pen and to be used with the same facility for writing.

Another object of the invention is to provide means for preventing overheating of the holder or body portion, so that the pen may be used for a long period of time without discomfort to the person writing therewith, and this end is accomplished by the use of heat dissipating elements which have relatively large surfaces cooled by the passage of air through the interior of the pen.

Another object of the invention is to provide an improved point of high electrical resistance and durable quality which may be readily formed to the shape of an ordinary writing pen point.

Another object of the invention is to provide convenient means for opening and closing the circuit to the pen point, such means being operable by a movement of the finger while grasping the pen in the customary manner for writing.

Still other more specific objects and advantages characteristic of our invention will become more fully apparent from the description hereinafter set forth of one embodiment or example of the invention, having reference to the accompanying drawing. Of the drawing:

Fig. I represents a perspective View of a pen of our invention showing the manner in which it is adapted to be used.

Fig. II represents alongitudinal cross section of the same.

Fig. III represents an enlarged longitudinal cross section of a portion of the pen.

Fig. IV represents an enlarged transverse section of the pen, taken as indicated by the lines IV--IV of Fig. III; and,

Fig. V represents a transverse section of the pen, taken as indicated by the lines V-V of Fig. II.

As shown in the drawing, the pen comprises generally a holder I of heat insulating material, a pair of spaced current carrying bars 2, 3, and an element 4 of relatively high electrical resistance bridging the ends of the bars and forming a pen point. A exible cable 5 leads to the rear end of the holder I, and has therein electric conductors B which are joined in a suitable manner to thebars 2,3 as indicated at 1 in Fig. II. At

their forward ends, the bars 2, 3 are preferably drilled for insertion and uniting thereto, as indicated at 8, of the ends of the wire 4, which forms the pen point.

The current carrying bars 2, 3 have a relatively large diameter and relatively large heat dissipating surfaces, as compared with the conducting wires 6, and they are desirably made of iron or other material having a relatively low electrical resistance and relatively good heat conducting quality. On the other hand, the wire 4 which forms the pen point is made of a material which is hard and durable, and is of relatively high electrical resistance. One material which has such qualities is known commercially as nichrom steel.

At the forward or writing end of the pen, the holder I has a multiplicity of closely spaced perforations 9 distributed over the surface and permitting the free flow of air through the interior of the holder around the exposed bars 2, 3. Inasmuch as the bars 2, 3 extend outwardly to a substantial distance beyond the writing end of the holder I, there is neither direct contact nor close heat exchange relation between the resistance wire 4 and the body of the holder I. Additional perforations are provided in the body of the holder I as indicated at I0, such openings being to the rear of the portion of the holder which is adapted to be grasped by the hand when writing. Accordingly, provision is made for the circulation of air through one set of openings into the interior of the holder and around the bars 2, 3, the air flowing outwardly through the other Set of openings, and carrying off the heat generated in the bars, thus eifectively cooling that portion of the pen which is held in the hand.

While the manner of incorporating the current carrying bars2,3 within the holder I may be varied tc considerable extent, the preferred construction involves a spacing member I2 at the forward end of the holder, which may form an integral part thereof, and which is of heat insulating material, and an additional spacing member I3, which may take the form of a separate disk, such spacing members having openings through which the bars 2, 3 are inserted. Between the spacing member I2 and the spacing member I3, the body of the holder I is interiorly formed to provide for substantially free circulation of air.

In order to control the operation of the pen, to minimize current consumption, and to safeguard against the possibility of accidental burning by contact with the pen point, improved means are provided for opening and closing the circuit to the pen point 4. As shown in the drawing, such circuit closing means desirably comprise a spring actuated switch I4 which is adapted to be closed by movement of the index finger while grasping the pen in the customary manner for Writing. The switch I 4 preferably takes the form of a ball with the upper portion thereof made of heat insulating material and the'lower portion of electrical conducting material. The ball I4 is attached to the end of a flat spring I5 which is secured by rivets IE to the body of the holder I, as indicated most clearly in Fig, 1H. The ball I is lodged in a hole Il and is adapted to be ringer pressed to close the electric circuit to the pen point 4.

When the pen of this invention is provided with finger operated circuit closing means, the current carrying bar 2 is conveniently made in two sections 2a, 2b. The adjacent ends of the sections 2a, 2b are screw threaded and engaged by correspondingly threaded spiders I'8a, I8b, which may be formed as an integral part of the body of the holder. The spiders Ia, |86 serve to provide a gap between the sections Zw, 2b, of the bar 2, the gap being normally open, but

adapted to be closed by movement of the ball I4. The particular construction of the spiders I8a.,

I8?)` is shown most clearly in Fig. IV, and it provides a minimum of obstruction to the circulation of air through the body of the holder I.

In order to secure the spacing member I3 inv place within the holder I, the current carrying bar'av is threaded as indicated at 2i) and engages a correspondingly threadedY opening in the spacing member I3. Obviously other means may be employed for maintaining the current carrying bars in xed position within the holder I, but one advantage of the illustrated construction is that it affords a substantially'rigid assembly. Moreover, while the pen holder I is shown as made of two sections joined together centrally of theA pen as indicated at 2l, the holder m-ay obviously be formed or molded in any desired manner. There is particular advantage, however, in forming both theholder I and the pen point 4 to shapes closely approximating an. ordinary ink pen and pen point. This facilitates manipulation of the pen, making it easier to write clearly and legibly.

It will be. noted that with the pen of this invention heat generated at the pen point 4 is carried back by the bars 2, 3. throughv the interior of the. holder rather than concentrated at the writing end of the pen. In this manner advantage is taken of the relatively large heat radiatingr surface, and the heat is dissipated rapidly by circulation of air throughthe interior of the pen.

The provision of a switch of the character described makes it possible for the writer to control effectively the operation of thepen by a simple movement of the nger, and it enables the use of the pen with comparative safety and with economy as to current consumption.

While we have described and. illustrated one particular example of a pen embodying our invention, it will be noted that various changes may be made in the form of the pen and the manner of constructing it, and that certain features or" the invention may at times be used to advantage without a corresponding use of other features, all without departing from the spirit of our invention as defined by the annexed claims.

Having thus described our invention, we claim:

Y 41. An electric pen comprising an insulating holder, current carrying barstherein of relatively good heat conducting material, low electrical resistance, and large exposed surface area, and a pen point element of relatively high electrical resistance bridging the ends of said bars, said bars extending throughout the portion of the holder adapted to be grasped by the hand when writing, and said holdery having openings therein disposed rearwardly of said portion and adjacent to the pen point element and being interiorly formed to provide for air circulation around said current carrying bars between said openings.

2. An electric pen comprising an insulating holder, current carrying bars therein of relatively good heat conducting material, low electrical resistance, and large exposed surface area, and a pen point element of relatively high electrical resistance bridging the ends of said bars, said bars extending throughout the portion of the holder adapted to be grasped by the hand when writing, and said holder having a set of openings disposed rearwardly of said portion, and an additional set of openings adjacent to the pen point element, and said holder being substantially imperforate throughout. the said han-d grasped portion and interiorly formed to provide for air circulation around said current carrying bars between said sets of openings.

3. An electric lpen comprising an insulatingv holder, current carrying bars therein of relatively good heat conducting material, low electrical re sistance, and large exposed surface area, perforated spacing membersv for maintaining said,`

bars in xed spaced relation within the holder, and a pe ipoint element of relatively high electricalw lice bridging the ends of said bars, said bars extending throughout. the portion of the holder adapted to be grasped by the hand whenl writing, and said holder having a set of openings. rearwardly of said portion and' an additional set of openings adjacent to the pen point element and being interiorly formed to provide for air circulation around said current carrying barsn between said' sets of openings.

4.'. An electric pen comprising an insulating holder, current carrying bars extending interiorly through the holder, perforated spacing members for maintaining said bars in xed position With.- Y

in the holder, said bars terminating in a relatively high resistance connecting wire serving'as a pen point, and one of said bars having a gap therein,

circuit closing means extending through the Wall of the holder and adapted to be -nger pressedv to close the gap aforesaid, and a spring urging" ball extending through the wall of the holderv and adapted to bel finger` pressed to close the gapy aforesaid, and a spring lurging said ball away from sai-d gap, the holder being interiorly formedV to provide for` air circulation throughout the: portion thereof which is adapted to be grasped by the hand.

ALLSTON JENKINS.

L. DAY?.Y PAUL R, REMJEP. 

